Originally thought to be coming from outside the school, the leak was traced by PSE&G to one of two boilers that heat the building, officials said.

Hoboken schools Superintendent Mark Toback said the faulty boiler at the school at 1100 Willow Ave. was shut down and repaired.

"The one boiler is able to maintaina comfortable temperature and everything is back to normal," Toback said.

Students and staff evacuated from the building Tuesday at 10:30 a.m. to Hoboken High School at 800 Clinton St., where parents were instructed to pick them up. School resumed yesterday morning at 8:15 a.m.

Officials had originally said the gas leak originated outside the school building.